An example of a vehicle operation supporting device in the prior art is the technology described in Japanese Kokai Patent Application No. 2005-125933. According to that technology, the distance between an obstacle and the vehicle is detected, and the risk potential with respect to the obstacle is calculated corresponding to the detected distance. When a steering reactive force is generated based on the risk potential, the driver is warned about approach of the vehicle to the obstacle, and approach of the vehicle to the obstacle is prevented.